The NATIONAL BOARD OF FIRE UNDERWRITERS OF THE UNITED STATES OF AMERICA has issued a set of rules and requirements, of which those relating to acetylene generators and plant are reproduced below. The underwriters state that, "To secure the largest measure of safety to life and property, these rules for the installation of acetylene gas machines must be observed." RULES FOR THE INSTALLATION AND USE OF ACETYLENE GAS GENERATORS. [Footnote: The "gallon" of these rules is, of course, the American gallon, which is equal to 0.83 English standard gallon.] The use of liquid acetylene or gas generated therefrom is absolutely prohibited. Failure to observe these rules is as liable to endanger life as property. To secure the largest measure of safety to life and property, the following rules for the installation of acetylene gas machines must be observed. _Class A.--Stationary Automatic Apparatus._ 1. FOUNDATIONS.--(_a_) Must, where practicable, be of brick, stone, concrete or iron. If necessarily of wood they shall be extra heavy, located in a dry place and open to the circulation of air. The ordinary board platform is not satisfactory. Wooden foundations shall be of heavy planking, joists or timbers, arranged so that the air will circulate around them so as to form a firm base. (_b_) Must be so arranged that the machine will be level and unequal strain will not be placed on the generator or connexions. 2. LOCATION.--(_a_) Generators, especially in closely built up districts should preferably be placed outside of insured buildings in generator houses constructed and located in compliance with Rule 9. (_b_) Generators must be so placed that the operating mechanism will have room for free and full play and can be adjusted without artificial light. They must not be subject to interference by children or careless persons, and if for this purpose further enclosure is necessary, it must be furnished by means of slatted partitions permitting the free circulation of air. (_c_) Generators which from their construction are rendered inoperative during the process of recharging must be so located that they can be recharged without the aid of artificial light. (_d_) Generators must be placed where water will not freeze. 3. ESCAPES OR RELIEF-PIPES.--Each generator must be provided with an escape or relief-pipe of ample size; no such pipe to be less than 3/4- inch internal diameter. This pipe shall be substantially installed, without traps, and so that any condensation will drain back to the generator. It must be carried to a suitable point outside the building, and terminate in an approved hood located at least 12 feet above ground and remote from windows. The hood must be constructed in such a manner that it cannot be obstructed by rain, snow, ice, insects or birds.